J. G. Thomson and Sinton (1912)[64] have obtained in cultures the various trypanosome forms of _T. gambiense_ seen in the fly’s main gut.
[64] _Annals Trop. Med. and Parasitol._, vi, p. 331.
Duke (1912)[65] found _T. gambiense_ in a species of antelope, the situtunga (_Tragelaphus spekei_), on Damba Island in Victoria Nyanza. Wild _G. palpalis_ could be infected therefrom. The antelope may then act as a sleeping sickness reservoir in that district, but men are apparently the chief reservoir.
[65] _Proc. Roy. Soc._, B, lxxxv, pp. 156, 483.
*Trypanosoma nigeriense*, Macfie, 1913.[66]
Macfie has recently (August, 1913) described a human trypanosome from the Eket district of Southern Nigeria. It is common in young people. The disease produced does not seem to be of a virulent type in Nigeria, and does not occur in epidemic form. In the early stages the glands of the neck are enlarged. In the later stages--cases of which are rarer--lethargy appears. The parasite is a polymorphic trypanosome, morphologically almost indistinguishable from _T. gambiense_, though it may be slightly shorter. Macfie recorded the occurrence in his preparations of a few trypanosomes appearing to have a flagellum free during their whole length. Some of the parasites, as seen in a sub-inoculated guinea-pig, are very small (8 µ long). Other trypanosomes have their nuclei displaced somewhat anteriorly. This parasite may only be a variety of _T. gambiense_. The parasite is perhaps spread by _Glossina tachinoides_.
[66] _Annals Trop. Med. and Parasitol._, vii, p. 339; viii, p. 379.
*Trypanosoma rhodesiense*, Stephens and Fantham, 1910.
The parasite was found in the blood of a young Englishman who had contracted sleeping sickness in the Luangwa Valley, North-eastern Rhodesia, in the autumn of 1909. The patient had never been in an area infested with _Glossina palpalis_.
(1) _Morphology._--The morphology of the parasite in man and sub-inoculated rats was studied by Stephens and Fantham in 1910.[67] They pointed out a morphological peculiarity in the presence of certain trypanosomes with posterior nuclei in sub-inoculated animals, that is, parasites in which the nucleus (trophonucleus) was situated towards the posterior or aflagellar end, close up to or even beyond the blepharoplast or kinetic nucleus (fig. 31, _4_, _5_). When the nucleus was beside the blepharoplast, the former was seen to be kidney-shaped (fig. 31, _4_). The posterior nuclear forms were of the stout and stumpy variety, and about 6 per cent. of the stumpy forms were found to have their nuclei displaced from the centre. The anterior or flagellar end of these trypanosomes often contained chromatoid granules. _T. rhodesiense_ varies in length from 12 µ to 39 µ[68]; short stumpy forms vary from 13 µ to 21 µ, intermediate forms from 21 µ to 24 µ, and long, slender forms from 25 µ onwards. The average length is 24·1 µ.